This invention relates to the processing of data from an image system, and more particularly to the processing of digital image data received from an optical document reading system.
Documents which are processed by an optical document reading system typically have one or more areas or "image fields" at various locations on the document which contain information, such as printed or written alphabetic or numeric characters for example. The document reading system scans the document and converts the information on the document into an output stream of digital image data.
The output data stream from the image system consists of equal size picture elements or PEL's corresponding to the digital video output from an optical scanner. The data stream is usually divided into scan lines consisting of a fixed number of PEL's. A common set of connected PEL's is referred to as an image field. A rectangular image field is completely defined by the index or value of the first and last scan lines, and the beginning and ending PEL locations.
In the past, a major problem of document image processing has been the high costs associated with handling and buffering of binary images. This is because the image fields of a document are typically extracted and placed in a buffer in their entirety before they are processed.
The present invention provides a dynamic field cut technique which utilizes the scan line as its elemental unit of data in controlling the concurrent extraction and processing of the individual image fields. This technique provides substantial savings in data handling and buffering costs over conventional field cut methods.